High air demand and high horsepower per cubic inch engines, like most internal combustion engines, require a proper mixture of fuel and air to be fed into the combustion chamber of the cylinders and these fuel to air ratios and fuel curve requirements can change for each section of the engine at both idle and at each range of the engines rpm band and even during different positions of the carburetors throttle valve (throttle blade) position. A common device for regulating the air/fuel mixture and delivering it to the combustion chamber is a carburetor. The carburetor controls the engine's fuel and air input and therefore greatly influences power output. The carburetor mixes fuel and air in the correct proportions for the engines rpm (revolutions per minute) and for the engine's varying load. The carburetor atomizes and vaporizes the fuel/air mixture to facilitate combustion. While fuel injection has replaced carburetors in many of today's vehicles, carburetors continue to be used in high performance vehicles (i.e., race cars) particularly where space, cost, or performance preferences dictate. Carburetors often have the same basic structure: a fuel inlet and reservoir (the fuel bowl assembly), which takes in and holds fuel for metering in the proper proportions; a main body, including a throttle valve (throttle blade) an air passage, which admits air in one end and discharges the fuel/air mixture from the other; and one or more fluid circuits connecting the fuel bowl assembly to the main body. The actual design and orientation of the structures varies widely depending on the size, configuration, and performance needs of the engine.
Engine's may employ many types of carburetor designs. The most popular example is the four barrel carburetor registered under U.S. Pat. No. 2,892,622 Inventor: C. R. Goodyear, Assignee: Holley Carburetor Company. A similar design for this patent application is shown in U.S. Pat. No. 4,670,195 issued to Robson; Richard E. G. (referred to herein as the Robson design). The mission of the Robson design appears to be that it was to simply improve fuel atomization. But different engine cylinders also require different ratios at different engine rpms for proper operation. The Robson design does not serve the engines particular requirements as it does not have the capability to alter the fuel curve for each quadrant of the single barrel. Prior art single venturi designs as shown in U.S. Pat. No. 3,758,082 issued to Kertell, did offer quadrant tuning of the venturi but once again did not offer quadrant tuning of the air to fuel ratio curve now did it allow for quadrant tuning of the idle air to fuel mixture. These missing capabilities are required on larger single barrel carburetors and especially when used on higher horsepower per cubic in engines as they are more sensitive and have more exacting demands in their engines air to fuel ratio needs. A carburetor without these air to fuel ratio tuning capabilities is unusable on a high horsepower per cubic inch engine. Higher powered engine's create more heat or less heat in some areas of the engine cylinder's and those hotter or cooler cylinder's will require richer or leaner air to fuel ratios as engine rpms vary. Also prior art did not have the capability of changing this air to fuel ratio curve as it exits the boosters as the engine rpms, engine loading and even the throttle blade/valve position is changed. An air to fuel ratio curve is an actual change in air to fuel ratio as the engine rpms increase or decrease. As an example, a typical performance engine tuned for maximum power will require a 13:1 air to fuel ratio. 13 parts air to 1 part fuel. But at lower rpms one section of the engine may require a ratio of 12.5:1 to keep it from detonating due to that section of the engine being hotter or other combustion effects.
However, since the introduction of larger single blade carburetors a need has been discovered for a true quadrant tunable single blade carburetors to meet the higher powered engines demands. True quadrant tuning of the metered fuel is especially required on larger single throttle blade designs, as during part throttle operation, the large single throttle blade design has an inherent flaw in that this much larger throttle blade will gather the bulk of the fuel that exits the boosters. This fuel will then roll down the back of the throttle blade and be distributed solely to the rear of the engine, making it run poorly due to excessive fuel being distributed to the rear and less fuel being distributed to the front during part throttle operation. So to remedy this condition, the rear quadrant of the booster (that distributes fuel into the rear portion of the single venturi) needs to be separately tunable to correct this issue. By utilizing a separate metering system, the single venturi design is to be calibrated to be much leaner during part throttle operation in the rear quadrant (the area of the venturi where the throttle blade drops down as the throttle blade is opened), so less fuel will run down the throttle blade during part throttle operation and will be distributed to the rear of the venturi during lower air speeds and part throttle operation. Consequently the front portion of the quadrant (the area where the throttle blade rises) needs to be tuned to be much richer (exactly the opposite direction to the rear quadrants needs) to remedy the situation created by the larger throttle blade robbing the fuel from the front quadrant of the venture during part throttle operation. However, when the throttle blade is rotated to a more vertical wide open throttle position, the fuel distribution in the single venturi needs to be once again restored to a more even air to fuel ratio as it exits the boosters. This is important to avoid the engine from now being too lean in the rear and too rich in the front during wide open throttle operation. The same issue apply when metering idle fuel into the engine.
The much larger blade requires that all four quadrants of the venture be fed and individually controlled in order to evenly supply idle fuel into the engine. Without this capability, the larger throttle blade design will only supply air to the rear of the engine and the engine will not ingest fuel into the rear cylinders and will not idle or will not idle properly. Prior art single venturi designs did not have an actual metering system that allowed these important tuning functions and prior art designs that incorporated a much smaller throttle blade probably did not require these capabilities. Prior art single barrel designs such as the Kertell design did allow the booster to be tuned to supply various amounts of fuel to each quadrant of the venturi but only in the area of having the ability to supply the same air to fuel ratio curve to the whole booster cluster. The Kertell design could in fact lean out the rear of the booster or a left rear quadrant of the booster, but it would maintain that same ratio at all times. The Kertell and other prior art single venturi designs do not allow each divided section of its single venturis' booster supplied fuel to be tuned to supply different volumes of fuel to each divided section of the booster at different air speeds (air/fuel ratio curve) nor did they allow each quadrant of the throttle blades perimeter to have controllable idle and transfer fuel (transfer fuel is fuel supplied during light part throttle operation). As a result those designs are incapable of properly controlling a larger single throttle blade carburetor design and filling the engine's needs.
Carburetors on performance engines disclosed in the aforementioned U.S. Pat. No. 2,892,622, have conventionally been of the four barrel type. This four barrel arrangement was to allow for better control of the engines quadrants. These four barrel carburetors were designed to supply the appropriate amount of air and fuel to each quadrant of the engine and by utilizing multiple metering systems it allowed for more precise tailoring of the engine's needs at varying loads, throttle positions and engine rpms. This is often a difficult task even with four barrel design carburetors. However, large single passage carburetors showed less eddy resistance (increased flow versus area) but these prior art single passage (single barrel) designs could not be built to allow for proper control of the air to fuel delivery process as a need was there for correcting the distribution of fuel into the intake manifold and the custom tailoring of the air to fuel ratio curve of each of the engines cylinders during varying loads, throttle blade/valve positions and engine rpms. This fuel curve and air to fuel ratio correction ability is required on any performance engine for maximum power and reliability as well as fuel economy. The intake manifold for the engines different cylinders are usually of different lengths and the fuel is not typically distributed evenly and this created a problem for large single barrel carburetors. A high horsepower per cubic inch multi cylinder engine will store and create various amounts of heat in each cylinder and as a result of its design, will require more or less fuel to be supplied to those hotter or cooler cylinders for maximum performance at varying loads and engine rpms to avoid damage. One solution proposed by U.S. Pat. No. 4,204,585 to Tsuboi et al., incorporated herein by reference, proposes using a carburetor for each cylinder of the engine in the case of a multi-cylinder engine. But this increases the complexity of the package, as well as requires accommodation in the engine envelope, which may already be cramped. This new design corrects the prior art single barrel carburetor designs inability to properly feed a high performance engine. It now has the ability to not only correct its air to fuel ratio (which prior art has employed) for each cylinder but it takes it a required step further and also incorporates a separate and completely independent metering system for each quadrant that allows for a change in the carburetor's air to fuel ratio curve for each divided section of the venture, at idle, transfer, part throttle and during wide open throttle operation. Prior art has not included a separate metering system for each quadrant of the venture nor has prior art even been equipped with an adjustable idle mixture system for each quadrant of the single barrel. These are options that present designs can achieve in four barrel carburetor designs, but have never been employed by prior art in a single barrel design as the complexity of incorporating them into the design was not solved by the prior art.